1. Field of the Invention
The present invention is related to eye surgery and, more particularly, to a device and method for retaining a lens capsule during ophthalmologic surgery, particularly cataract surgery and intraocular lens implantation surgery.
2. Description of the Related Art
In the field of ophthalmology, cataract surgery and intraocular lens implantation surgery are now common, with high surgical success rates and improved rates of postoperative recovery of the patient's visual functions. In cataracts, the intraocular lens becomes clouded, causing impairment of visual acuity, and the most widely used technique for treatment of this symptom is phacoemulsification/aspiration surgery.
In this surgical technique, the anterior capsule of the lens, which is a clear membrane enclosing the surface of the lens, is incised using an incision needle (anterior capsulotomy). Next, a phacoemulsification/aspiration needle is inserted into the eye via the incision wound in the corneal limbus, and the lens cortex and nucleus are emulsified and aspirated out via the site of the anterior capsulotomy. Finally, an intraocular lens is implanted in the bag-shaped lens capsule. Accordingly, it is vitally important in these phacoemulsification/aspiration and intraocular lens implantation procedures to maintain the intracular lens capsule, which holds the intraocular lens in position, in a round bag shape.
The lens is connected to a transparent tissue composed of countless thin fibers referred to as the Zinn zonule which runs from near the equatorial region of the lens capsule to the ciliary body, and this maintains the lens' shape and position. During surgery, the lens is subjected to external pushing and pulling forces in response to movement of a retractor and the phacoemulsification/aspiration needle. The Zinn zonule is also subjected to stress accompanying this movement of the lens, but this usually does not result in damage to the Zinn zonule because the healthy zonule is ordinarily sufficiently strong.
However, in elderly patients, patients with poor pupil dilation, patients with pseudoexfoliation syndrome, etc., it is frequently the case that the Zinn zonule is inherently weak, partially torn or out of position. In such patients, there is an increased risk of complications such as luxation of the lens if the zonule ruptures or the extent of this rupture expands, or dislocation of the luxated lens into the vitreous cavity.
U.S. Pat. No. 6,183,480 of Mackool describes a device for stabilizing the lens capsule. Mackool's device is a hook-shaped lens capsule stabilizer in which the margin of anterior capsulotomy with a brittle or ruptured Zinn zonule is subjected to traction together with the ring of the iris. Mackool's device has a hook-shaped, curved portion which catches and pulls on the margin of the capsulotomy to retract same, but it cannot be used in situations where the incised anterior capsule shows fissures. Cases of a brittle or ruptured Zinn zonule are treated as refractory cases of cataract surgery, and it is known that in such cases, extraction of the lens nucleus is difficult, and complications such as lens dislocation, posterior capsule rupture, intraocular lens displacement, and dislocation into the vitreous cavity may occur.
Maintenance of favorable dilation status is one of the conditions for safely performing cataract surgery. Eye drops are ordinarily used to dilate the pupil, but some patients with a history of conditions such as glaucoma or uveitis fail to respond to eye drops, making it impossible to sufficiently dilate the pupil.
In such poorly dilated eyes, a surgical auxiliary device referred to as an iris retractor has conventionally been used in order to forcibly dilate the pupil. When a metal iris retractor is used in patients with a brittle or ruptured Zinn zonule, the edge of the iris (papillary margin) and the margin of anterior capsulotomy are pulled together, subjecting the lens capsule to traction as well, but it is impossible to secure the proper shape of the lens capsule as the retraction site is a margin of the capsulotomy only.
In the lens capsule-stabilizing device developed by Mackool, the retraction site also is a margin of the capsulotomy only, making it impossible to secure a sufficient bag-like shape of the lens capsule.
Capsular tension rings and fixation arms of intraocular lenses (haptics) are used in order to secure a round shape of the equatorial region of the lens capsule. Capsular tension rings are used to prevent after-cataracts by preventing proliferation and extension of the epithelial cells of the anterior lens into the posterior capsule and intraocular lenses are used for correcting visual acuity. In cases where the Zinn zonule ruptures, capsular tension rings and intraocular lenses may be dislocated into the vitreous cavity resulting in the possible need for resurgery.